DOI: 10.1175/JCLI-D-17-0187.1
Scopus记录号: 2-s2.0-85047074931
论文题名: Twentieth-century climate change over Africa: Seasonal hydroclimate trends and sahara desert expansion
作者: Thomas N. ; Nigam S.
刊名: Journal of Climate
ISSN: 8948755
出版年: 2018
卷: 31, 期: 9 起始页码: 3349
结束页码: 3370
语种: 英语
英文关键词: Climate models
; Hadley circulation
; Multidecadal variability
; Rainfall
; Surface temperature
; Trends
Scopus关键词: Agriculture
; Climate change
; Expansion
; Landforms
; Rain
; Rain gages
; Agricultural economy
; Hadley circulation
; Multidecadal variability
; Observational analysis
; Seasonal temperature
; Surface air temperatures
; Surface temperatures
; Trends
; Climate models
英文摘要: Twentieth-century trends in seasonal temperature and precipitation over the African continent are analyzed from observational datasets and historical climate simulations. Given the agricultural economy of the continent, a seasonal perspective is adopted as it is more pertinent than an annual-average one, which can mask offsetting but agriculturally sensitive seasonal hydroclimate variations. Examination of linear trends in seasonal surface air temperature (SAT) shows that heat stress has increased in several regions, including Sudan and northern Africa where the largest SAT trends occur in the warm season. Broadly speaking, the northern continent has warmed more than the southern one in all seasons. Precipitation trends are varied but notable declining trends are found in the countries along the Gulf of Guinea, especially in the source region of the Niger River in West Africa, and in the Congo River basin. Rainfall over the African Great Lakes-one of the largest freshwater repositories-has, however, increased. It is shown that the Sahara Desert has expanded significantly over the twentieth century, by 11%-18% depending on the season, and by 10% when defined using annual rainfall. The expansion rate is sensitively dependent on the analysis period in view of the multidecadal periods of desert expansion (including from the drying of the Sahel in the 1950s-80s) and contraction in the 1902-2013 record, and the stability of the rain gauge network. The desert expanded southward in summer, reflecting retreat of the northern edge of the Sahel rainfall belt, and to the north in winter, indicating potential impact of the widening of the tropics. Specific mechanisms for the expansion are investigated. Finally, this observational analysis is used to evaluate the state-of-the-art climate simulations from a comparison of the twentieth-century hydroclimate trends. The evaluation shows that modeling regional hydroclimate change over the African continent remains challenging, warranting caution in the development of adaptation and mitigation strategies. © 2018 American Meteorological Society. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/111552
Appears in Collections: 气候减缓与适应
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作者单位: Department of Atmospheric and Oceanic Science, University of Maryland, College Park, College Park, MD, United States; Jefferson Science Fellow, The National Academy of Sciences, Engineering and Medicine, Washington, DC, United States
Recommended Citation:
Thomas N.,Nigam S.. Twentieth-century climate change over Africa: Seasonal hydroclimate trends and sahara desert expansion[J]. Journal of Climate,2018-01-01,31(9)